Delete fucking everything is what happens when you're about to get party-V& so you delete every shred of evidence you possibly can in an attempt to have no evidence of the stupid shit you have done. If nobody can see what you did, then it's just like nothing bad ever happened! Everything will be fine then and your secrets will be safe forevar!

Of course this never works because screenshots, the Wayback Machine, and even downloaded archives of entire websites are real things that make sure that your stupid mistakes will be remembered. If anything, attempting to delete everything simply shows the world that, yes, you had things to hide and, yes, they were right to think you were a total scumbag. In the case that you actually attempted to delete everything on a hard drive Pedo-style, then you're still fucked as even a 100% reformatted harddrive can still have information restored from it and the nice folks down at the FBI are VERY good at recovering information from even the most broken hard drives.

An alternate usage of this term is a popular form of wiki vandalism in which large ammounts of information are deleted all at once in the hopes that nobody will ever notice. This is because there is no such thing as a deletion log or edits log and each user page doesn't come with a 100% complete history of every single edit you have ever done so not even the admins will ever know you did it! And I have a bridge in New Jersey to sell you for cheap. Fer reals.